darwin: Use -Os instead of -O2

(cherry picked from commit 456dbb143a)

configs/darwin

@@ -20,9 +20,9 @@ DEFINES =  -D_DARWIN_C_SOURCE -D_POSIX_SOURCE -D_POSIX_C_SOURCE=199309L \
 
 ARCH_FLAGS += $(RC_CFLAGS)
 
-CFLAGS =  -g -O2 -Wall -Wmissing-prototypes -std=c99 -ffast-math -fno-strict-aliasing \
+CFLAGS =  -ggdb3 -Os -Wall -Wmissing-prototypes -std=c99 -ffast-math -fno-strict-aliasing \
 	-I$(INSTALL_DIR)/include $(OPT_FLAGS) $(PIC_FLAGS) $(ARCH_FLAGS) $(ASM_FLAGS) $(DEFINES)
-CXXFLAGS =  -g -O2 -Wall -fno-strict-aliasing \
+CXXFLAGS =  -ggdb3 -Os -Wall -fno-strict-aliasing \
 	-I$(INSTALL_DIR)/include $(OPT_FLAGS) $(PIC_FLAGS) $(ARCH_FLAGS) $(ASM_FLAGS) $(DEFINES)
 
 # Library names (actual file names)